Reinforced interleaved watermarking

ABSTRACT

In one embodiment, an apparatus includes a processor to receive a primary video, select first sections of the primary video in which to include units of data for use in watermarking, select second sections of the primary video, each second section including a first data item without which at least one video unit of the primary video cannot be rendered or rendered correctly, replace each first section with at least two watermark variants, replace each second section with at least two watermark variant decoys, wherein the apparatus is operative to operate in an environment including an end-user device operative to select one of the watermark variants for each first section and one of the watermark variant decoys for each second section for rendering as part of an interleaved video stream including the primary video in order to embed units of data of an identification in the interleaved video stream.

TECHNICAL FIELD

The present disclosure generally relates to interleaved watermarking.

BACKGROUND

Interleave-based broadcast video watermarks are watermarks whose payloaduniquely identifies an end-user device and/or a subscriber potentiallyillegally streaming content over the internet. The watermarks areinserted into selectable video data at the broadcast headend to achievea higher level of security. The video data arriving at the end-userdevices may be selectively rendered in order to embed suitable watermarkdata in a resulting composite video.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be understood and appreciated more fullyfrom the following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a view of interleaved watermarking using two variant seriesconstructed and operative in accordance with an embodiment of thepresent disclosure;

FIG. 2a is a view of interleaved watermarking using a first protectivefeature constructed and operative in accordance with an embodiment ofthe present disclosure;

FIG. 2b is a view of interleaved watermarking using a second protectivefeature constructed and operative in accordance with an embodiment ofthe present disclosure;

FIG. 2c is a view of interleaved watermarking using another protectivefeature constructed and operative in accordance with an embodiment ofthe present disclosure;

FIG. 3 is a view of a headend system constructed and operative inaccordance with an embodiment of the present disclosure; and

FIG. 4 is a view of an end-user device constructed and operative inaccordance with an embodiment of the present disclosure.

DESCRIPTION OF EXAMPLE EMBODIMENTS Overview

There is provided in accordance with an embodiment of the presentdisclosure, an apparatus including a processor to receive a primaryvideo, select a plurality of first sections of the primary video inwhich to include units of data for use in watermarking, select aplurality of second sections of the primary video, each one of theplurality of second sections including a first data item without whichat least one video unit of the primary video cannot be rendered orcannot be rendered correctly, replace each one first section of theplurality of first sections with at least two watermark variants, eachone of the at least two watermark variants of the one first sectionincluding a watermarked version of the one first section, and replaceeach one second section of the plurality of second sections with atleast two watermark variant decoys, each one of the at least twowatermark variant decoys including the one second section, a memory tostore data used by the processor, wherein, the apparatus is operative tooperate in an environment including an end-user device operative toselect one of the at least two watermark variants for each one of theplurality of first sections and one of the at least two watermarkvariant decoys for each one of the plurality of second sections forrendering as part of an interleaved video stream including the primaryvideo in order to embed units of data of an identification in theinterleaved video stream.

Encoded Versus Encrypted

The term “encoded” is used throughout the present specification andclaims, in all of its grammatical forms, to refer to any type of datastream encoding including, for example and without limiting the scope ofthe definition, well known types of encoding such as, but not limitedto, MPEG-2 encoding, H.264 encoding, VC-1 encoding, and syntheticencodings such as Scalable Vector Graphics (SVG) and LASER (ISO/IEC14496-20), and so forth. It is appreciated that an encoded data streamgenerally requires more processing and typically more time to read thana data stream which is not encoded. Any recipient of encoded data,whether or not the recipient of the encoded data is the intendedrecipient, is, at least in potential, able to read encoded data withoutrequiring cryptanalysis. It is appreciated that encoding may beperformed in several stages and may include a number of differentprocesses, including, but not necessarily limited to: compressing thedata; transforming the data into other forms; and making the data morerobust (for instance replicating the data or using error correctionmechanisms).

The term “compressed” is used throughout the present specification andclaims, in all of its grammatical forms, to refer to any type of datastream compression. Compression is typically a part of encoding and mayinclude image compression and motion compensation. Typically,compression of data reduces the number of bits comprising the data. Inthat compression is a subset of encoding, the terms “encoded” and“compressed”, in all of their grammatical forms, are often usedinterchangeably throughout the present specification and claims.

Similarly, the terms “decoded” and “decompressed” are used throughoutthe present specification and claims, in all their grammatical forms, torefer to the reverse of “encoded” and “compressed” in all theirgrammatical forms.

The terms “scrambled” and “encrypted”, in all of their grammaticalforms, are used interchangeably throughout the present specification andclaims to refer to any appropriate scrambling and/or encryption methodsfor scrambling and/or encrypting a data stream, and/or any otherappropriate method for intending to make a data stream unintelligibleexcept to an intended recipient(s) thereof. Well known types ofscrambling or encrypting include, but are not limited to DES, 3DES, andAES. Similarly, the terms “descrambled” and “decrypted” are usedthroughout the present specification and claims, in all theirgrammatical forms, to refer to the reverse of “scrambled” and“encrypted” in all their grammatical forms.

Pursuant to the above definitions, the terms “encoded”; “compressed”;and the terms “scrambled” and “encrypted” are used to refer to differentand exclusive types of processing. Thus, a particular data stream maybe, for example:

-   -   encoded, but neither scrambled nor encrypted;    -   compressed, but neither scrambled nor encrypted;    -   scrambled or encrypted, but not encoded;    -   scrambled or encrypted, but not compressed;    -   encoded, and scrambled or encrypted; or    -   compressed, and scrambled or encrypted.

Likewise, the terms “decoded” and “decompressed” on the one hand, andthe terms “descrambled” and “decrypted” on the other hand, are used torefer to different and exclusive types of processing.

DETAILED DESCRIPTION

Reference is now made to FIG. 1, which is a view of interleavedwatermarking using two variant series 10 (variant series 10-0 andvariant series 10-1) constructed and operative in accordance with anembodiment of the present disclosure. It should be noted that unlessotherwise mentioned, the various functions described with reference toFIGS. 1-2 c are performed by a Headend or content provider or contentsupplier or content server or another server or processor locatedremotely to end-user devices. A plurality of sections 15-1 are selectedfrom the primary video 12. Each section 15-1 is processed to: (i)include watermarking data in that section 15-1 yielding a watermarkvariant 16-0 for inclusion in the variant series 10-0; and (ii) includedifferent watermarking data in that same section 15-1 yielding awatermark variant 16-1 for inclusion in the variant series 10-1. In anend-user device, the end-user device selects one of the watermarkvariants 16 for each of the sections 15-1 for rendering as part of aninterleaved video stream including the primary video 12 in order toembed units of data of an identification in the interleaved videostream, as will be described in more detail below.

The sections 15-1 selected from the primary video 12, and included inthe variant series 10 as the watermark variants 16, are removed from theprimary video 12. The watermark variants 16 may be packaged in atransport stream with the same packet ID (PID) as the primary video 12.In such a case the different watermark variants 16 are signaled usingsuitable signals for example, but not limited to, using adaptationfields which are not typically encrypted. Alternatively, other timedmetadata, for example, but not limited to, in a non-encrypted metadatastream, may be used to signal the watermark variants 16. Alternatively,the watermark variants 16 may be packaged in secondary video streamswith different PIDs for each of the variant series 10-0 and 10-1. Insuch a case the primary video 12 also typically has a different PID fromthe variant series 10-0 and 10-1.

The primary video 12 is encrypted with an encryption key which may bechanged periodically, e.g., per cryptoperiod. The variant series 10-0,“Series 0”, is encrypted with an encryption key and the variant series10-1, “Series 1”, is encrypted with a different encryption key. Theencryption keys used to encrypt the variant series 10 may be changedperiodically, for example, but not limited to, every cryptoperiod ormore or less frequently than every cryptoperiod described in more detailbelow. Each watermark variant 16 in each variant series 10 may be doublyencrypted, first with the encryption key designated for that variantseries 10 and then with the encryption key used to encrypt the primaryvideo 12 or alternatively first with the encryption key used to encryptthe primary video 12 and then with the encryption key designated forthat variant series 10.

An end-user device receiving the primary video 12 and the two variantseries 10 is provided with the decryption keys or information forgenerating the decryption keys to decrypt the primary video 12 and thevariant series 10. The information for generating the decryption keysmay be included in at least one entitlement control message (ECM) withthe decryption keys being changed every cryptoperiod. Additionally oralternatively, decryption keys may be sent out-of-band from thetransmission of the variant series 10 and the primary video 12 and thedecryption keys may therefore by changed periodically and possiblyout-of-sync with the cryptoperiods. The decryption keys may also bebased on information stored in the end-user devices or using any othermethod known in the art for delivering decryption keys.

A processor such as a secure processor in the end-user device may beprogrammed with logic for deciding whether to generate the decryptionkey for decrypting the watermark variant 16-0 or the watermark variant16-1 for each occurrence of the watermark variants 16. The logic may bebased on which bit of an identification (ID) is to be embedded in theinterleaved video stream. The knowledge of which bit needs to beembedded in the interleaved video stream may be included in the ECM(s)or in an index encoded in the primary video 12, by way of example only.The secure processor may also have access to the ID that needs to beembedded, for example, the ID may be embedded in the secure processor.So for example, if a current unit of data that should be embedded in thevideo rendered by the end-user device is a zero, the secure processorgenerates the decryption key for decrypting the watermark variant 16-0of the variant series 10-0. On the other hand, if the current unit ofdata that should be embedded in the video rendered by the end-userdevice is a one, the secure processor generates the decryption key fordecrypting the watermark variant 16-1 of the variant series 10-1. Foreach subsequent watermark variant pair 16-0, 16-1, the secure processorgenerates a decryption key so that selection of the watermark variant 16for decrypting and rendering by the end-user device is performed basedon the data which needs to be embedded in the resulting interleavedvideo stream for rendering by the end-user device.

Alternatively, the end-user device uses decryption keys which aredelivered to the end-user device or are pre-stored on the end-userdevice, for example, by a manufacture. The decryption keys are stored onthe device, securely if possible. The decryption keys may then be usedto decrypt one of the watermark variants 16 for each occurrence of thewatermark variants 16 (e.g., one watermark variant 16 is decrypted foreach watermark variant pair 16). Typically one key is used for eachoccurrence of the watermark variants 16. So if there are 100 units ofdata in an ID for watermarking, the end-user device is provided with 100keys selected from a possible 200 keys. Alternatively, the delivered orpre-stored keys may be combined with other key generation information,for example, delivered key generation information in order to generatedecryption keys for decrypting one of the watermark variants 16 for eachoccurrence of the watermark variants 16. It will be appreciated thatdelivered decryption keys or the pre-stored decryption keys may includemetadata which is used by the end-user device to match the correctdecryption key with the correct watermark variant 16 and/or additionalkey generation information received by the end-user device.

The different watermark variants 16 decrypted and interleaved with theprimary video 12 in the end-user devices then serve to uniquely identifyeach end-user device or subscriber, as the choice of which watermarkvariants 16 to decrypt and render is determined based on an IDassociated with each respective end-user device or a subscriber or smartcard, by way of example only. The embedded ID may be an identificationof the end-user device or a subscriber or a smart card etc., or variousencodings of the identification by various coding theory techniques suchas error correcting codes and anti-collusion codes, by way of example.

It should be noted that using more than two variant series 10 may beimplemented for use in watermarking. For example, using four variantsseries 10 may enable embedding two bits per watermark variant 16, e.g.,each watermark variant 16 may embed either 00, 01, 10 or 11.

It will be appreciated that each unit of an ID may be repeated asnecessary in the variant series 10 to make the resulting watermarkrobust enough, for example, but not limited to, for error correctionpurposes.

Reference is now made to FIG. 2a , which is a view of interleavedwatermarking using a first protective feature constructed and operativein accordance with an embodiment of the present disclosure. One possibleweakness in the watermarking scheme described above with reference toFIG. 1 is that an attacker trying to circumvent watermarking may decideto render the primary video 12 while filtering out the variant series10. In real world settings, video decoders can compensate for missing oromitted macroblocks in the frames quite well and the degradation of theviewing experience may be minimal, while the watermark signal iscompletely destroyed. The above omission attack may be more impracticalor even prevented if protection is implemented such that an attack by anattacker causes degraded video playback thus reducing the rendered videoquality enough to discourage someone from viewing such a degraded video.

A set of critical video elements may be defined, and some or allsections, e.g., packets or slices, of the primary video 12 that includethe critical video elements are moved from the primary video 12 to eachof the variant series 10-0, 10-1 (in addition to generating thewatermark variants 16 in the variant series 10). In such a way, anattacker filtering out the variant series 10 ends up filtering out thecritical video elements as well as filtering out the watermark variants16 and the decoder may not have enough data in the remaining primaryvideo 12 to allow for any or almost any video playback or whichnegatively impacts the user viewing experience sufficiently.

The set of critical video elements may be defined to include, by way ofexample only, the network abstraction layer (NAL) headers for all (orsome) NALs (or a subset thereof) in the Video Coding Layer (VCL), inother words the NAL headers for all (or some) slices (or a subsetthereof). Alternatively or additionally, the set of critical videoelements may be defined to include the NAL headers for all (or some)sequence parameter set (SPS) or the NAL headers for all (or some)picture parameter set (PPS) NALs (or a subset thereof), or all or someof the SPS NALs, or all or some of the PPS NALs, or all or some of theslice headers themselves, or some slice body packets or any combinationof the above.

It should be noted that some sets of video elements may not besufficient to prevent video playback. As an example, if only the NALheaders of I-slices were to be moved to the variant series 10 and thenremoved by an attacker, then the P and B-slice NAL headers are stillparsed and consumed by the decoder, and even though P and B slices areinter-predicted, they contain enough intra-predicted macroblocks duringscene changes that eventually, some quite reasonable video playback maytake place.

The protective measure against the omission attack is now described inmore detail. In addition to selecting the sections 15-1 (FIG. 1) fromthe primary video 12, a plurality of sections 15-2 are also selectedfrom the primary video 12. Each section 15-2 includes a data itemdefined as a critical video element described above. The data item isused in rendering a part 17 (for example) of the primary video 12 suchthat the part 17 (e.g., at least one video unit, such as at least oneframe or macroblock of video) cannot be rendered or cannot be renderedcorrectly without the data item.

The variant series 10 are generated to include the watermark variants 16and the moved sections 15-2. For each of the sections 15-2, that section15-2 is moved to each variant series 10. The sections 15-2 in thevariant series 10 are also referred to as “watermark variant decoys” asthey provide protection against an omission attack directed towardsfiltering out the watermark variants 16. Although the watermark variants16 are different in each of the variant series 10, the sections 15-2 aregenerally identical in each of the variant series 10. When the variantseries 10 are encrypted, an attacker will generally not be able to tellthe sections 15-2 apart in the variant series 10. The sections 15-2included in the variant series 10 typically do not include watermarkingdata.

The sections 15-1, 15-2 selected from the primary video 12 and includedin some form in each variant series 10 are removed from the primaryvideo 12. Nevertheless, the watermark variants 16 and the sections 15-2may be packaged with the same packet ID (PID) as the primary video 12.Alternatively, the watermark variants 16 and the sections 15-2 may bepackaged in secondary video streams with different PIDs for each variantseries 10-0 and 10-1. In such a case, the primary video 12 alsotypically has a different PID from the variant series 10-0 and 10-1.

Reference is now made to FIG. 2b , which is a view of interleavedwatermarking using a second protective feature constructed and operativein accordance with an embodiment of the present disclosure. The firstprotective feature, namely, adding the sections 15-2 (the “watermarkvariant decoys”) to the variant series 10 may not be strong enough aloneto prevent an attack as some statistical tests may be used by attackersto correctly tell apart the sections 15-2 from the watermark variants 16in the variant series 10. In such a case, an attacker may simply filterout the watermark variants 16 and not the sections 15-2 from the variantseries 10. An example of an attack is given below with reference to FIG.2b and another example is given below with reference to FIG. 2 c.

To try to mask statistical patterns that attackers may utilize, astatistical masking choice of additional sections 15-3, e.g., transportstream packets or slices, are selected from the primary video 12 andmoved to each of the variant series 10 (in addition to the sections 15-2and the watermark variants 16 included in the variant series 10). Foreach of the sections 15-3, that section 15-3 is moved to each variantseries 10. The sections 15-3 when moved to each variant series 10 arealso referred to as “statistical decoys”. The statistical model drivingthe masking choice is typically based on the statistical patterns thatattackers may use to tell apart the watermark variants 16 (e.g.,watermarked packets or slices), from the sections 15-2 (e.g., criticalvideo element packets), such that the masking choice masks thestatistical pattern(s). It will be appreciated that the statisticalmasking may be applied in sections of the video that include watermarkvariants 16 and sections of video which do not include the watermarkvariants 16 do not necessarily need the statistical masking to beapplied. It will be appreciated that the statistical masking choicedepends on the statistical patterns that may be revealed by the sections15-2 and the watermark variant 16 in the variant series 10. Two examplesof statistical masking are described below, one with reference to FIG.2b and one with reference to FIG. 2 c.

The sections 15-3 may be randomly or pseudo-randomly selected from theprimary video 12. In the example of FIG. 2b , the sections 15-3 areselected by randomly or pseudo-randomly selecting a plurality oflocations in the primary video 12 from which to select the sections15-3. The locations may be selected by applying a randomly orpseudo-randomly independent choice for each location, e.g., for eachpacket or slice in the primary video 12. By way of example, suppose thatthe watermark variants 16 and the sections 15-2 (e.g., critical videoelements) individually fit within a single transport stream (TS) packet,and that watermarking data is included in one type of slice (for exampleB slices). Due to the different size distributions of I, P and B slicesin normal H.264 video and the fact that some of the slice-types may notbe used for watermarking, then the differences between the positions inwhich the packets in the variant series 10 appear in the whole TS mightleak information about which packets include watermark data and whichinclude critical video elements. By selecting the sections 15-3 from theprimary video 12 for inclusion in the variant series 10 based on aBernoulli random variable with a p parameter that is higher than theinverse of a small percentile of the distribution of distances betweenthe positions of the packets in the variant series 10, the existingposition differences are “broken” by the newly introduced TS packetsthat are interspersed among the existing TS packets of the variantseries 10 and the pattern used by the attacker is lost. It will beappreciated that (pseudo-)random selection is not limited to Bernoullichoice and that any (pseudo-)random selection method may be used. By wayof example and clarification, suppose that the distances betweenpositions of the TS packets in the variant series 10 (both watermarkingand critical video elements) is distributed with 10% percentile forinter-packet distance 200, 50% percentile (median) for inter-packetdistance 450 and 90% percentile for inter-packet distance 1500. Then bymaking a Bernoulli choice for every TS packet in the primary video 12with p equals 1/180, on average every 180th TS packet from the primaryvideo 12 is selected for inclusion in the variant series 10, and as aresult the pattern of the differing gaps between the TS packets in thevariant series 10 is masked.

The sections 15-1, 15-2, 15-3 selected from the primary video 12 andincluded in some form in the variant series 10 are removed from theprimary video 12. Nevertheless, the watermark variants 16 and thesections 15-2, 15-3 may be packaged with the same packet ID (PID) as theprimary video 12. Alternatively, the watermark variants 16 and thesections 15-2, 15-3 may be packaged in secondary video streams withdifferent PIDs for each of the variant series 10-0 and 10-1. In such acase the primary video 12 also typically has a different PID from thevariant series 10-0 and 10-1. It will be appreciated that any timecodesassociated with the sections 15-1, 15-2, 15-3 in the primary video 12are typically associated with the watermark variants 16 and the sections15-2, 15-3 in the variant series 10.

Reference is now made to FIG. 2c , which is a view of interleavedwatermarking using another protective feature constructed and operativein accordance with an embodiment of the present disclosure. FIG. 2cprovides another example of masking a statistical model by selecting thesections 15-3 from the primary video 12 in a random or pseudo-randomway. In contrast to FIG. 2b , where the locations of the sections 15-3are selected randomly or pseudo-randomly, in FIG. 2c , a length of eachsection 15-3 is selected randomly or pseudo-randomly as will now bedescribed in more detail. A length for each section 15-3 is selectedrandomly or pseudo-randomly. Additionally, the location of each section15-3 in the primary video stream 14 may be selected to be adjoining oneof the sections 15-2 so that each section 15-2 has an adjoining section15-3 in each variant series 10 or the location of each section 15-3 inthe primary video stream 14 may be selected randomly or pseudo-randomly.The above may be illustrated by way of example. Suppose that thestatistical pattern used by attackers to distinguish between thewatermark variants 16 and sections 15-2 (e.g., watermark variant decoys)is based on the lengths of the watermark variants 16 and the sections15-2. For example, the sections 15-2 may have a length of 1, whereas thewatermark variants 16 may have a length that is Poisson distributed withlambda equal to 6. Then to thwart an attack, the sections 15-3 may bechosen randomly or pseudo-randomly with a length distribution of lambdaequal to 5 and added immediately after or before the sections 15-2(e.g., the watermark variant decoys), thereby masking out the patternthat was used by attackers to distinguish the watermark variants 16 fromthe sections 15-2. It should be noted that more than one masking methodmay be applied to the variant series 10.

Reference is now made to FIG. 3, which is a view of a broadcast headendsystem 18 constructed and operative in accordance with an embodiment ofthe present disclosure. Throughout the description below reference isalso made to: the variant series 10, primary video 12 and the watermarkvariants 16 of FIGS. 1 and 2 a-c; the sections 15-1 of FIG. 1; thesections 15-2 of FIGS. 2a-c ; the parts 17 of FIG. 2a ; and the sections15-3 of FIGS. 2b -c.

The headend 18 includes an encoder 20, a watermark processor 34, an ECMgeneration processor 22, an encryption processor 24, a multiplexer 26, atiming processor 28 and transmission equipment 30. The elements 20, 22,24, 26, 28, 30, 34 may be combined together in any suitable combinationimplemented as one or more processors.

The headend 18 is described by way of example only. It will beappreciated that the primary video 12 and the variant series 10 may begenerated in any suitable processing device or devices, for example, butnot limited to a content server or content processor and transmitted toend-user devices using any suitable medium, for example, but not limitedto, satellite, cable, internet protocol (IP), cellular, local networkand/or wireless network, by any suitable method, for example, but notlimited to broadcast, multi-cast, unicast, VOD etc. Alternatively, theprimary video 12 and the variant series 10 may be prepared for disposingon a non-transient medium such as a compact disk (CD) or digital videodisk (DVD), by way of example only.

The encoder 20 is operative to receive and encode the primary video 12.The watermark processor 34 is operative to receive the encoded primaryvideo 12 from the encoder 20. The watermark processor 34 is operative toselect the sections 15-1 of the primary video 12 in which to includeunits of data for use in watermarking. The watermark processor 34 isoperative to select the sections 15-2 of the primary video 12. Eachsection 15-2 includes a data item without which at least one video unitof the primary video 12 cannot be rendered or cannot be renderedcorrectly. The data item is selected from one of the following: anetwork abstraction layer (NAL) header; a slice header; and a slice bodypacket, by way of example only. Optionally, the watermark processor 34is operative to randomly or pseudo-randomly select the sections 15-3 ofthe primary video 12. The watermark processor 34 may be operative torandomly or pseudo-randomly select locations in the primary video 12from which to select the sections 15-3. Additionally or alternatively,the watermark processor 34 is operative, for each section 15-3, torandomly or pseudo randomly select a length for that section 15-3.

The watermark processor 34 is operative to replace each section 15-1with at least two watermark variants 16 such that for each section 15-1,each watermark variant 16 of that section 15-1 includes a watermarkedversion of that section 15-1. The different watermarks variants 16 ofthe same section 15-1 include different watermarking data. The watermarkprocessor 34 is operative to replace each section 15-2 with at least twowatermark variant decoys such that for each section 15-2, each watermarkvariant decoy includes that section 15-2, but does not includewatermarking data. The watermark processor 34 is operative to replaceeach section 15-3 with at least two statistical decoys such that foreach section 15-3, each statistical decoy includes that section 15-3,but does not include watermarking data. The watermark variants 16, thewatermark variant decoys and the statistical decoys form part of thevariant series 10 as described above with reference to FIGS. 2a -c.

The variant series 10 may be generated as secondary streams withdifferent PIDs from the PID of the primary video 12 or with the same PIDas the primary video 12 with signaling, as discussed above, forsignaling the data of each variant series 10. The replaced sections15-1, 15-2, 15-3 are removed from the primary video 12 even though thesections 15-2, 15-3 and the watermark variants 16 may have the same PIDas the primary video 12 in certain embodiments. It should be noted thatreplacing each section 15-1, 15-2, 15-3 of the primary video 12 with two(or more) other sections 15-1, 15-2, 15-3, as described above, may beachieved by duplicating each section 15-1, 15-2, 15-3 once (or more ifthere a three or more variant series 10) (with changes for watermarkingas necessary for the sections 15-1) and moving the original section15-1, 15-2, 15-3 (with changes for watermarking as necessary for thesections 15-1) from the primary video 12 to the variant series 10.

The encryption processor 24 is operative to: encrypt each watermarkvariant 16 of a same section 15-1 with a different encryption key;encrypt each watermark variant decoy of a same section 15-2 with adifferent encryption key; and each statistical decoy of a same section15-3 with a different encryption key. It should be noted that one ormore watermark variants 16 and/or watermark variant decoy(s) and/orstatistical decoy(s) of the same variant series 10 (e.g., variant series10-0 or variant series 10-1) may share the same encryption key. Theencryption processor 24 is operative to encrypt the encoded and amendedprimary video 12 with its encryption key. The encrypted variant series10 may also be encrypted again with the encryption key used to encryptthe encoded and amended primary video 12. Alternatively, the variantseries 10 may be first encrypted with the encryption key used to encryptthe encoded and amended primary video 12 and then with the encryptionkeys of the variant series 10. The encryption processor 24 may beoperative to change the different encryption keys periodically. If ECMsare being used for decryption purposes, the ECM generation processor 22is operative to generate one or more entitlement control messages foreach cryptoperiod.

If the variant series 10 do not have the same PID as the primary video12 it may be necessary to arrange the placement of the packets of thevariant series 10 among the packets of the primary video 12 in atransport stream in the same order that the sections 15-1, 15-2, 15-3were included in the primary video 12 before the sections 15-1, 15-2,15-3 were removed from the primary video 12. In such a case, the timingprocessor 28 may be operative to arrange the packets of the variantseries 10 among the variant series 10 according to timecodes ortimestamps associated with the packets in the series 10 and the primaryvideo 12. The multiplexer 26 is operative to multiplex the variantseries 10 in the transport stream with the primary video 12. Thetransmission equipment 30 is operative to transmit the transport streamto end-user devices. It should be noted that for the sake of simplicity,the terms primary video 12 and variant series 10 is used in thespecification and claims to refer to a non-encoded version or an encodedversion but not encrypted version or an encoded and encrypted version orany other version of the primary video 12 and the variant series 10.

Reference is now made to FIG. 4, which is a view of an end-user device38 constructed and operative in accordance with an embodiment of thepresent disclosure. The end-user device 38 includes a receiver 40, ademultiplexer 42, a decryption processor 44 and a decoder 46. Thereceiver 40 is operative to receive a transport stream 48 including theencrypted and encoded variant series 10 and the encrypted and encodedprimary video 12. By way of introduction, the end-user device 38 selectsone of the watermark variants 16 for each section 15-1 and one of thewatermark variant decoys for each section 15-2 and one of thestatistical decoys for each section 15-3 (if included) for rendering aspart of an interleaved video stream including the primary video 12 inorder to embed units of data of an identification in the interleavedvideo stream. The end-user device 38 is now described in more detail.

The demultiplexer 42 is operative to demultiplex the variant series 10and the primary video 12 included in the transport stream 48. Thedecryption processor 44 is operative to: receive decryption keys and/ordecryption key generation information and/or one or more ECMsperiodically, for example, for each cryptoperiod. A secure processor(for example, in a smart card 50 or in the end-user device 38) may beoperative to generate the decryption keys and/or select the decryptionkeys that were delivered to, or pre-stored on, the end-user device 38.

If the decryption keys for the variant series 10 are generated in theend-user device 38, the secure processor may be programmed with thelogic for deciding which decryption keys to generate. The logic istypically based on which bit of the ID needs to be embeddedcorresponding to one of the variant series 10. The knowledge of whichbit needs to be embedded may be included in the ECM(s) or in an indexencoded in the primary video 12, or the ID may be embedded in the secureprocessor, by way of example only.

The decryption processor 44 is operative to decrypt the encrypted andencoded primary video 12 and the relevant parts of the relevantencrypted and encoded variant series 10 using the generated and/ordelivered and/or pre-stored decryption keys. The decoder 46 is operativeto decode the decrypted primary video 12 and the decrypted selectedvariant series 10. The decoder 46 is generally operative to reassemblethe decoded primary video 12 and the decoded selected variant series 10in the order in which the primary video 12 and the variant series 10were disposed in the transport stream 48 as an interleaved video stream.

In practice, some or all of these functions, including the functions ofthe watermark processor 34, may be combined in a single physicalcomponent or, alternatively, implemented using multiple physicalcomponents. These physical components may comprise hard-wired orprogrammable devices, or a combination of the two. In some embodiments,at least some of the functions of the processing circuitry may becarried out by a programmable processor under the control of suitablesoftware. This software may be downloaded to a device in electronicform, over a network, for example. Alternatively or additionally, thesoftware may be stored in tangible, non-transitory computer-readablestorage media, such as optical, magnetic, or electronic memory.

It is appreciated that software components may, if desired, beimplemented in ROM (read only memory) form. The software components may,generally, be implemented in hardware, if desired, using conventionaltechniques. It is further appreciated that the software components maybe instantiated, for example: as a computer program product or on atangible medium. In some cases, it may be possible to instantiate thesoftware components as a signal interpretable by an appropriatecomputer, although such an instantiation may be excluded in certainembodiments of the present disclosure.

It will be appreciated that various features of the disclosure whichare, for clarity, described in the contexts of separate embodiments mayalso be provided in combination in a single embodiment. Conversely,various features of the disclosure which are, for brevity, described inthe context of a single embodiment may also be provided separately or inany suitable sub-combination.

It will be appreciated by persons skilled in the art that the presentdisclosure is not limited by what has been particularly shown anddescribed hereinabove. Rather the scope of the disclosure is defined bythe appended claims and equivalents thereof.

What is claimed is:
 1. An apparatus comprising: a memory device; and aprocessor coupled to the memory device, wherein the processor isoperative to: receive a primary video; select a plurality of firstsections of the primary video in which to include units of data for usein watermarking; select a plurality of second sections of the primaryvideo, each one of the plurality of second sections including a firstdata item without which at least one video unit of the primary videocannot be rendered or cannot be rendered correctly; replace each onefirst section of the plurality of first sections with at least twowatermark variants, each one of the at least two watermark variants ofthe one first section including a watermarked version of the one firstsection; replace each one second section of the plurality of secondsections with at least two watermark variant decoys, each one of the atleast two watermark variant decoys including the one second section; andselect one of the at least two watermark variants for each one of theplurality of first sections and one of the at least two watermarkvariant decoys for each one of the plurality of second sections forrendering as part of an interleaved video stream including the primaryvideo in order to embed units of data of an identification in theinterleaved video stream, wherein each one of the at least two watermarkvariant decoys of each one of the plurality of second sections does notinclude watermarking data.
 2. The apparatus according to claim 1,wherein each one of the plurality of second sections includes a firstdata item without which at least one video unit of the primary videocannot be rendered.
 3. The apparatus according to claim 1, wherein eachone of the plurality of second sections includes a first data itemwithout which at least one video unit of the primary video cannot berendered correctly.
 4. The apparatus according to claim 1, wherein theprocessor is further operative to: encrypt each one of the at least twowatermark variants of a same one of the plurality of first sections witha different encryption key; and encrypt each one of the at least twowatermark variant decoys of a same one of the plurality of secondsections with a different encryption key.
 5. The apparatus according toclaim 1, wherein the first data item is selected from one of thefollowing: a network abstraction layer (NAL) header; a slice header; anda slice body packet.
 6. The apparatus according to claim 1, wherein theprocessor is further operative to: randomly or pseudo-randomly select aplurality of third sections of the primary video; and replace each onethird section of the plurality of third sections with at least twostatistical decoys, each one of the at least two statistical decoysincluding the one third section.
 7. The apparatus according to claim 6,wherein each one of the at least two statistical decoys of each one ofthe plurality of third sections does not include watermarking data. 8.The apparatus according to claim 6, wherein the processor is operativeto randomly or pseudo-randomly select a plurality of locations in theprimary video from which to select the plurality of third sections. 9.The apparatus according to claim 6, wherein the processor is operativeto, for each one third section of the plurality of third sections,randomly or pseudo randomly select a length for the one third section.10. A method comprising: receiving a primary video; selecting aplurality of first sections of the primary video in which to includeunits of data for use in watermarking; selecting a plurality of secondsections of the primary video, each one of the plurality of secondsections including a first data item without which at least one videounit of the primary video cannot be rendered or cannot be renderedcorrectly; replacing each one first section of the plurality of firstsections with at least two watermark variants, each one of the at leasttwo watermark variants of the one first section including a watermarkedversion of the one first section; and replacing each one second sectionof the plurality of second sections with at least two watermark variantdecoys, each one of the at least two watermark variant decoys includingthe one second section, wherein each one of the at least two watermarkvariant decoys of each one of the plurality of second sections does notinclude watermarking data.
 11. The method according to claim 10, whereineach one of the plurality of second sections includes a first data itemwithout which at least one video unit of the primary video cannot berendered.
 12. The method according to claim 10, wherein each one of theplurality of second sections includes a first data item without which atleast one video unit of the primary video cannot be rendered correctly.13. The method according to claim 10, further comprising: encryptingeach one of the at least two watermark variants of a same one of theplurality of first sections with a different encryption key; andencrypting each one of the at least two watermark variant decoys of asame one of the plurality of second sections with a different encryptionkey.
 14. The method according to claim 10, wherein the first data itemis selected from one of the following: a network abstraction layer (NAL)header; a slice header; and a slice body packet.
 15. The methodaccording to claim 10, further comprising: randomly or pseudo-randomlyselecting a plurality of third sections of the primary video; andreplacing each one third section of the plurality of third sections withat least two statistical decoys, each one of the at least twostatistical decoys including the one third section.
 16. The methodaccording to claim 15, wherein each one of the at least two statisticaldecoys of each one of the plurality of third sections does not includewatermarking data.
 17. The method according to claim 15, furthercomprising randomly or pseudo-randomly selecting a plurality oflocations in the primary video from which to select the plurality ofthird sections.
 18. The method according to claim 15, furthercomprising, for each one third section of the plurality of thirdsections, randomly or pseudo randomly selecting a length for the onethird section.
 19. A non-transitory computer readable medium comprisinginstructions which when executed perform a method comprising: receivinga primary video; selecting a plurality of first sections of the primaryvideo in which to include units of data for use in watermarking;selecting a plurality of second sections of the primary video, each oneof the plurality of second sections including a first data item withoutwhich at least one video unit of the primary video cannot be rendered orcannot be rendered correctly; replacing each one first section of theplurality of first sections with at least two watermark variants, eachone of the at least two watermark variants of the one first sectionincluding a watermarked version of the one first section; replacing eachone second section of the plurality of second sections with at least twowatermark variant decoys, each one of the at least two watermark variantdecoys including the one second section; and selecting one of the atleast two watermark variants for each one of the plurality of firstsections and one of the at least two watermark variant decoys for eachone of the plurality of second sections for rendering as part of aninterleaved video stream including the primary video in order to embedunits of data of an identification in the interleaved video stream,wherein each one of the at least two watermark variant decoys of eachone of the plurality of second sections does not include watermarkingdata.
 20. The non-transitory computer readable medium according to claim19, wherein the instructions which when executed perform the methodfurther comprising: encrypting each one of the at least two watermarkvariants of a same one of the plurality of first sections with adifferent encryption key; and encrypting each one of the at least twowatermark variant decoys of a same one of the plurality of secondsections with a different encryption key.